A Label-Free Electrochemical Aptasensor Based on Screen Printed Carbon Electrodes With Gold Nanoparticles-Polypyrrole Composite for Detection of Cardiac Troponin I

Cardiac troponin I (cTnI) is a specific biomarker in the diagnosis of acute myocardial infarction (AMI). In this study, a label-free electrochemical aptasensor was developed for the detection of cTnI using an aptamer probe and conductive polypyrrole (PPy)-gold nanoparticles (AuNPs) as electrode substrate. The surface modification of the electrode was characterized by cyclic voltammetry (CV) and square wave voltammetry (SWV) electrochemical methods, scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray spectroscopy (EDX) analysis. SWV was also used to evaluate the analytical performance of the developed aptasensor using 5 mM [Fe(CN)6]3-/4- as a redox mediator. A detection limit of 25 pg mL−1 was obtained with a linear detection range from 50 to 500 pg mL−1. The proposed aptasensor exhibited good selectivity and appropriate sensitivity for clinical diagnostics compared with enzyme-linked immunosorbent assay (ELISA) analysis, allowing rapid, quantitative, and label-free detection of cardiac markers.